I don't think this is the comparison you are looking for. The XL2536 is a 144hz monitor with DyAc. You probably want to compare the XL2540 and XL2546 instead, rather than comparing a 144hz and 240hz monitor, since obviously the 240hz monitor will have better blur reduction just by the higher refresh rate it can be used at!

The difference between the XL2540 and the XL2546 is that the XL2540 supports Adaptive Sync (Freesync) and the XL2546 does NOT.The XL2540 has Benq Blur Reduction disabled (normal users can't enable it; it must be forced on in the service menu, but that's easy to do). The XL2546 has DyAC (which is Benq Blur Reduction, renamed for marketing purposes) enabled by default, which can be forced off in the service menu as well. It is unknown whether Freesync (Adaptive Sync) will work on the XL2546 when you forcibly disable DyAc (as blur reduction and freesync can not be used at the same time; trying to enable blur reduction on the XL2540 will stop freesync from working).

No one knows yet afaik, if blur reduction would look better on the XL2546 vs XL2540.

Unsure but reportedly roughly similar at the same strobe length/phase setting.

The DyAc models uses voltage-boosting to flash brighter. It is over 300 nits in strobed mode -- about 4x brighter than the average 2013-era LightBoost monitor. Most LightBoost monitors couldn't break 100 nits.